Hyperbaric oxygen and testicular damage and fertility

Zusammenfassung Männliche Ratten zeigen nach einmaliger oder wiederholter stark erhöhter O₂-Zufuhr (3–5 at) Krämpfe und Lungenschäden und zum Teil Absterben. Schädigungen der Spermatogenese oder der Fertilität traten nicht auf.     

Brain damage in rats following pentylenetetrazole and high pressure oxygen

Résumé La pentylénetétrazole (PTZ) et l'oxygène à haute pression (OHP) ont des propriétés en commun; tous deux causent des convulsions et du dommage aux poumons chez les rats. Elles diffèrent en ce que l'OHP — mais non pas la PTZ — produit au cerveau une paralysie spastique. On a trouvé que la PTZ, donnée avant et non pas après l'exposition des rats à l'OHP, réduit la paralysie du cerveau.     

Mating competitiveness and fertility of thiotepa-sterilized flies

Summary In the present investigation, an attempt has been made to study the mating competitiveness and fertility of males as well as females ofDacus dorsalis Hendel (Diptera: Tephritidae) treated topically with thiotepa. In the mixed population, treated flies of either sex were found to be sexually more vigorous than untreated flies. However when the mating competitiveness of either sex was determined separately using various methods, treated males were found not to differ significantly in sexual competitiveness from untreated flies. Receptivity of treated and untreated females to males was also studied by the single choice method. Thiotepa-treated and untreated females were found to be equally receptive to males.     

Leptin signaling and circuits in puberty and fertility

Leptin is an adipocyte-derived hormone involved in a myriad of physiological process, including the control of energy balance and several neuroendocrine axes. Leptin-deficient mice and humans are obese, diabetic, and display a series of neuroendocrine and autonomic abnormalities. These individuals are infertile due to a lack of appropriate pubertal development and inadequate synthesis and secretion of gonadotropins and gonadal steroids. Leptin receptors are expressed in many organs and tissues, including those related to the control of reproductive physiology (e.g., the hypothalamus, pituitary gland, and gonads). In the last decade, it has become clear that leptin receptors located in the brain are major players in most leptin actions, including reproduction. Moreover, the recent development of molecular techniques for brain mapping and the use of genetically modified mouse models have generated crucial new findings for understanding leptin physiology and the metabolic influences on reproductive health. In the present review, we will highlight the new advances in the field, discuss the apparent contradictions, and underline the relevance of this complex physiological system to human health. We will focus our review on the hypothalamic circuitry and potential signaling pathways relevant to leptin’s effects in reproductive control, which have been identified with the use of cutting-edge technologies of molecular mapping and conditional knockouts.     

Effects of cyclohexylamine on rat fertility

Résumé Des rats mâles traités oralement avec du sulfate de cyclohexylamine (220 mg/kg/jour) ont été accouplés à des femelles traitées ou non avec du sulfate de cyclohexylamine. Dans les 2 cas, il y a eu des descendants moins nombreux que chez les contrôles. Les résultats suggèrent que l'effet est transmis par les mâles traités et est, peut-être, causé par un dommage génétique exprimé avant l'implantation de l'embryon.     

Similarities between metallothionein and low molecular weight testicular cadmium-binding protein

The incorporation of 35S-cysteine and 3H-glutamic acid was studied in mouse hepatic and renal metallothionein and in testicular cadmium-binding protein of similar molecular weight. Preferential incorporation of 35S-cysteine over 3H-glutamic acid was observed not only in hepatic and renal metallothionein, but also in testicular cadmium-binding protein. When the antigenic reactivity of these proteins was compared, all three proteins reacted with the metallothionein antibody. These similarities suggest that the low molecular weight testicular cadmium-binding protein is apparently metallothionein.     

Similarities between metallothionein and low molecular weight testicular cadmium-binding protein

Summary The incorporation of³⁵S-cysteine and³H-glutamic acid was studied in mouse hepatic and renal metallothionein and in testicular cadmium-binding protein of similar molecular weight. Preferential incorporation of³⁵S-cysteine over³H-glutamic acid was observed not only in hepatic and renal metallothionein, but also in testicular cadmium-binding protein. When the antigenic reactivity of these proteins was compared, all three proteins reacted with the metallothionein antibody. These similarities suggest that the low molecular weight testicular cadmium-binding protein is apparently metallothionein.     

DNA damage repair and transcription

Silencing of DNA repair genes plays a critical role in the development of the cancer because these genes, functioning normally, would prevent the accumulation of mutations leading to carcinogenesis. Epigenetic gene silencing is an alternative mechanism to genetic gene aberration, inactivating those genes in cancer. DNA methylation and histone modification are the major factors for epigenetic regulation of gene expression. Here, we describe recent advances in understanding of epigenetic silencing of DNA repair genes and their epigenetic mechanisms involving DNA methylation and histone modification.     

DNA damage repair and transcription

DNA mutations and aberrations are a problem for all forms of life. Eukaryotes specifically have developed ways of identifying and repairing various DNA mutations in a complex and refractory chromatin environment. The chromatin structure is much more than a packaging unit for DNA; it is dynamic. Cells utilize and manipulate chromatin for gene regulation, genome organization and maintenance of genome integrity. Once a DNA aberration has occurred, the various DNA repair machineries interact with chromatin proteins, such as the histone variant H2A.X, and chromatin remodeling machines of the SWI/SNF family to gain access and repair the lesion in a timely manner. Recent studies have thus begun to address the roles of chromatin proteins in DNA repair as well as to dissect the functions of DNA repair machinery in vitro on more physiological, nucleosomal templates.     

DNA damage repair and transcription

Double-strand breaks arise frequently in the course of endogenous - normal and pathological - cellular DNA metabolism or can result from exogenous agents such as ionizing radiation. It is generally accepted that these lesions represent one of the most severe types of DNA damage with respect to preservation of genomic integrity. Therefore, cells have evolved complex mechanisms that include cell-cycle arrest, activation of various genes, including those associated with DNA repair, and in certain cases induction of the apoptotic pathway to respond to double-strand breaks. In this review we discuss recent progress in our understanding of cellular responses to DNA double-strand breaks. In addition to an analysis of the current paradigms of detection, signaling and repair, insights into the significance of chromatin remodeling in the double-strand break-response pathways are provided.     

Control of sperm motility and fertility: Diverse factors and common mechanisms

Spermatozoa generated in the testis are immature and incompetent for fertilization. During their journey toward the egg, the sperm acquire fertility and achieving fertilization. These sperm modifications to ensure fertilization are induced by many female or male extra-sperm factors: for example, sperm motility-activating factors from the egg jelly, sperm attractants from the eggs, and decapacitation factors from the seminal plasma. The factors controlling sperm fertility are myriad and species specific; they may be peptides, sugar chains, or small organic compounds. Nevertheless, the fundamental mechanisms underlying fertilization must be common among all animals; increase in [Ca²⁺]_i triggers all the steps in the process of fertilization, and cAMP plays important roles in many steps. Elucidating the dynamic functional and morphological changes in sperm cells is important for understanding the regulation of fertilization. Here, we introduce the diversity and generality of the control of sperm fertility. Received 28 April 2008; received after revision 13 June 2008; accepted 17 June 2008     

2-Br-alpha-ergokryptin: influence on fertility and lactation in the rat

The effects of alpha-ergocryptin and 2-bromo-alpha-ergocryptin on fertility and lactation in rats were studied. The inhibitory actions of alpha-ergocryptin on fertility and lactation in the rat are altered differentially in the 2-bromo derivative of this ergot alkaloid. It is therefore unlikely that the fertility-inhibiting and the lactation inhibiting effects of 2-bromo-alpha-ergocryptin are governed by a single mechanism of action.     

On the biosynthesis of testicular steroids in vitro and its inhibition

Zusammenfassung Der Seitenkettenabbau von C₂₁-Steroiden zu Androgenen in Rattentesteshomogenat erwies sich abhängig von der Konzentration der Vorstufen und konnte durch gewisse Pyridinderivate präferentiell blockiert werden.